My sizes are out

[Doddy]

Apologies - somewhat out of context. My reference to "noise" is related to babble rather than advice and to the value (or lack thereof) to the continued thread, and not a suggestion at all of electrical noise.

For absolute clarity - I do not mean electrical noise, for the reasoned evidence that Jazz gives.

[Desertboy]

No No No don't go complicating shit with that it's too consistent to be noise. It would be random and happening all over the place if it was noise.

Still haven't had an answer to if the tool has been measured.?

12.68mm I just doubled checked it now.

[JAZZCNC]

Apologies - somewhat out of context. My reference to "noise" is related to babble rather than advice and to the value (or lack thereof) to the continued thread, and not a suggestion at all of electrical noise.

For absolute clarity - I do not mean electrical noise, for the reasoned evidence that Jazz gives.

Ah ok my apologies also, now I read it again in this context I see it, I didn't before and just saw electrical noise and with you being an electronics Wizz and the other electronic bull shit that's going on in another thread I thought OH NO please don't go there...

[phill05]

Have you tried with a different vernier caliper or always the same one?

[Desertboy]

Have you tried with a different vernier caliper or always the same one?

Always the same one but you can see a mm on a ruler which I also tried, the bit is a 1/2" trend router bit, and it's in a 1/2" collet so I think my calipers aren't the issue here.

The pocket even using measuring tape I can see are 1mm undersized.

BUT this gap is meant to be 100cm so the only thing I can think off is the controller is offsetting the tool.




Thinking I might need to connect the X, Y & Z to a breakout board and do a test cut from linuxcnc super slow to see if that shows the same size issue.

[JAZZCNC]

This is a wild shot but suppose must be asked.! . . .You have trammed the spindle haven't you.? Does the bottom of the pocket measure same as the top.?

[Desertboy]

This is a wild shot but suppose must be asked.! . . .You have trammed the spindle haven't you.? Does the bottom of the pocket measure same as the top.?

I can't remember if I did now, I've had the Z off a few times including changing the gantry rails, did I tram it last time?

Will go check shortly.

[JAZZCNC]

I can't remember if I did now, I've had the Z off a few times including changing the gantry rails, did I tram it last time?

Will go check shortly.

Actually, on reflection, it wouldn't make any difference the size would still be correct it's just your pocket walls would be a parallelllllll gram or what ever they are called..

[pippin88]

Have you measured your backlash? You need to check backlash.

[Doddy]

A couple of experiments for you to try.

*** CAUTION: Hand coded G-Code and un-tested. Sit next to your E-Stop!!! ***

test2.nc

This should slowly rock the X-axis by 0.5mm (or 18 degrees on a 1610 screw) - wrap a bit of tape around the x-axis screw with a visible tail and run this g-code through the controller and observe the tape. The G-code has got a feed rate of 10mm/min so my poor maths suggests around 3 seconds to go 0.5mm (18 degrees) and 3 seconds to go back to 0 (0 degrees). It repeats... a few times. No spindle and no z-movement.

This is just to verify that there's no backlash compensation active erroneously or not in the controller. You'll have to eyeball the 18 degrees rotation on the screw/tape.

Remove tape.

test.nc

This one cuts two pocket outlines - with your 12.7mm milling bit, starts at (0,0) and cuts a 3-tooth comb with a positive displacement on X, 50mm between teeth. After the 3rd tooth it reverses and cuts another 2 teeth offset in Y 30mm back the other way also 50mm apart. This to verify again that there's no backlash effects or compensation in operation.

Sorry, that's all I can think of at the moment.